Old Weapon Gives Precision Punch to Helicopters

What combat helicopters and unmanned aircraft in Afghanistan need in a hurry is an inexpensive, lightweight rocket that can be fired with enough accuracy to guide itself through a window-size target from outside the range of small-arms and light anti-aircraft fire.

The U.S. Navy believes it has the answer in a modified version of an unguided, Vietnam War-era rocket. The Advanced Precision Kill Weapon System (APKWS) II has already hit a basketball-size target at a range of 5 km (3 mi.).

BAE Systems intends to deliver the next batch of its low-rate-production APKWS directly to the U.S. Marine Corps for shipment to operational units. The first 325 missiles had completed delivery to the Navy in December, and the second lot of 600 will be dispatched in early fiscal 2012. With the end of operational testing in January, a full-rate-production decision for 1,000 missiles a year is expected to follow soon.

There is a rapid-deployment effort to arm the MQ-8B Fire Scout rotary-wing unmanned aerial system (UAS).

“APKWS is what we plan to put on [the MQ-8B] in the near future,” says Navy Capt. Brian Corey, program manager for the missile. “We expect that to be the Navy Department's first armed UAS. We could put a three-tube launcher on each of the two stations on a Fire Scout for a total of six rounds. The number of rounds actually on board depends on what other payloads are carried and the length of the mission.”

A Joint Concept Technology Demonstration also is underway to equip fixed-wing aircraft with the missile, which is being modified to survive a tougher, high-speed environment in the Air Force/Marine Corps project. The initial goal is to install the weapon on AV-8B and A-10 ground attack aircraft. The first operational launch of the missile from a fixed-wing aircraft, a modified AT-6 Texan II trainer, was made in mid-January. The combination developmental and operational test was conducted at Eglin AFB, Fla., using a lengthened launcher to protect the mid-body sensor system from damage by the firing of adjacent missiles. The APKWS rocket is usually bundled seven to a launcher. The Eglin tests also are part of a program to increase the firepower of light helicopters and fixed-wing attack aircraft.

The Marines' aim is to field APKWS on the AH-1W and UH-1Y helicopters first. “Then we'd like to see it on the AH-1Z . . . for its first deployment,” says Marine Corps Lt. Col. Matt Sale, air-to-ground weapons requirement officer. “Depending on how long the legacy F/A-18s are going to be around, that could be the next logical step.”

Combat in Afghanistan is generating the pressing need for precise rapid-fire missile systems on Marine helicopters.

“What's important to us is an appropriate target and weapons match,” says Lt. Col. Raymond Schreiner, lead H-1 test pilot for VX-31 at the China Lake, Calif., Naval Air Warfare Center. That means minimum collateral damage from small-yield precision weapons like the APKWS missile's 10-lb., Mk. 151 and Mk. 152 warheads. Logistics also offer an advantage, since many 2.75-in. rockets and warheads are already in place in theater and only guidance sections have to be delivered.

“The capability that APKWS provides is well suited for current operations,” says Sale. “Marine Corps headquarters is confident of a fielding decision early in the year. With APKWS, you can increase the volume of precision fire by carrying 7-14 missiles on each aircraft. Depending on the success of the program in the next year or two, we'll look at expanding envelopes and other material solutions.”

One idea is to adapt the package to the longer-range 5-in. Zuni rocket, which the Navy has in large numbers. However, it would be impossible for the larger rocket to be carried by UAS and helicopters in the same numbers.

As part of the APKWS's operational testing, the missile was subjected to a number of variables including altitude, airspeed, range to target, laser code, lighting conditions, target type and movement. Evaluations involved a threshold range of 5 km and an objective range of 8 km.

“As far as operational availability, the current effort is integrated. Developmental and operational testers are working side-by-side and we are evaluating two aircraft simultaneously,” says Schreiner. “We're minimizing the number of test resources required . . . that will answer both the developmental and operational requirements and minimize the schedule.”

The test program has yielded improvements including the ability to protect the missiles. The rocket pods have been extended to keep the mid-body guidance section out of the path of debris. Wing-slot seals have been added to keep particulate matter off the optics and protect them from blast damage.

“We worked with BAE about getting the wing-slot seals right,” says Corey. “That required a delicate engineering balance because we needed a seal that was affordable but rugged enough to protect the rocket and withstand the captive-carry environment on helicopters. Yet it needed to fracture to deploy the wings.”

The test results are promising.

“We had failures in testing, but when we put [the guidance units] on the flight line they worked. They're accurate and hitting well within requirements. The aircrew—if the targeting system camera is good enough—can put this thing through a window.” Targets included pickup trucks, lightly armored vehicles, walls of various construction types, moving targets and simulated gun positions.

The Navy took over the APKWS program from the Army in 2008 to fill the gap between the service's short-range airborne cannon and machine guns and Lockheed Martin's long-range, high-precision Hellfire anti-armor missile carried by helicopters. Hellfires cost roughly $68,000 each and weigh 100 lb. In comparison, the mid-range APKWS has a 10-lb. warhead for low collateral damage, is estimated by non-BAE analysts to cost $10,000 per missile, weighs roughly 32 lb. and has the precision to go through a window 5 km away. Moreover, the weapon is a threat to moving targets since it has flaperons to make high-speed flight corrections.

During this initial phase, BAE Systems developed a simple guidance package that did not require communications with its launch aircraft.

“Any airplane that can shoot an unguided 2.75-inch rocket can shoot an APKWS,” Corey says. “The only thing required to launch it is a 28-volt fire signal from the airplane. All the precision takes place after the rocket is launched. No integration with the platform, no signal transfers, no software updates are required.”